Immunohistochemical localization of parvalbumin calcium-binding protein in the heart tissues of various species.

Parvalbumin (PV), a cytoplasmic high-affinity Ca(2+)-binding protein, was recently identified in rat heart tissue and has been implicated in mediating relaxation in cardiac myocytes. The presence of PV in the heart of mouse, chicken, rabbit and pig was studied using immunohistochemistry. PV immunoreactivity (PV-ir) was identified in the heart of all four species. All cardiac myocytes of each species had an identical pattern of PV-ir in their cytoplasm. The highest intensity of PV-ir was observed in mouse and chicken cardiac myocytes. The intensity of PV-ir was lower in rabbit cardiac myocytes and lowest in pig cardiac myocytes compared to those of chicken and mouse. PV-ir was observed in the walls of all four cardiac chambers (left and right atria and left and right ventricles), with the left ventricle, in general, having the highest labeling intensity. The intensity of PV-ir may be correlated with the physical activity of the heart of each species. Some potential applications of these data for treatment of human diastolic heart dysfunctions are discussed.